Lake Hallwil

Hallwilersee, beside the village of Birrwil in the Seetal valley, is the largest lake in the Swiss canton of Aargau. Its southern tip reaches into the canton of Lucerne. The lake stretches roughly 8.4 km in length, measures up to 1.5 km across and drops to 47 m at its deepest point, with an average depth near 28 m.

Where is Lake Hallwil, and what feeds it?

The lake sits on the southern edge of Aargau, mostly within the Lenzburg and Kulm districts (about 47°17′ N, 8°12′ E). Its main inflow is the Aabach, which arrives from neighbouring Lake Baldegg. Birrwil and Beinwil am See lie on the shore, while Hallwyl Castle stands near the northern end.

What can you do here?

Walking the shoreline is the classic outing. The path runs through Birrwil and Boniswil to Hallwyl Castle; the stretch from Beinwil am See to the castle is about 8.3 km and takes around two hours. You can shorten a loop via Birrwil by taking a boat, operated by the local company Hallwilersee AG. In summer people swim and try water sports, and the quieter reed edges suit birdwatching.

Are there rules to know?

The lake is listed in the Swiss federal inventory of landscapes of national importance (BLN). Much of the shore remains undeveloped, and dogs must be kept on a lead inside the nature reserve. Stay on marked paths and keep clear of the reeds so nesting birds are not disturbed.

How do you get to Birrwil?

Birrwil lies in the Seetal, within reach of the main cities of northern and central Switzerland. Drive or use public transport from Aarau, Lenzburg or Lucerne; once there, walking or cycling along the lakeside roads is easiest. Check the ship timetable on the operator's website before you travel.

When should you visit?

Late spring, summer and early autumn work best: paths are dry, boats run regularly and the water is warm enough for a swim. Outside the season the lake is calmer and good for a long walk, though boat services are reduced, so confirm the schedule first.

Frequently asked questions

How big is Hallwilersee? About 8.4 km long, up to 1.5 km wide and 47 m deep at the maximum.

Which canton is it in? Mostly Aargau; the southernmost part belongs to Lucerne.

How long is the walk from Beinwil am See to Hallwyl Castle? Around 8.3 km, or roughly two hours on foot.

Can I bring a dog? Yes, but in the nature reserve dogs must stay on a lead.

Can I shorten the hike? Yes, part of the route around Birrwil can be replaced by a boat trip on the lake.